Generally, users and service providers require communication services be available regardless of time and location, and with a high quality at a low cost. There are provided an Orthogonal Frequency Division Multiplexing (OFDM) scheme, a Single Carrier Frequency Domain Equalization (SC-FDE) scheme, and the like to achieve a high speed data transmission rate.
For a receiver for performing frequency domain equalization to equalize distortion of a signal transmitted from a transmitter through a wireless channel, a wireless channel state may be required to be estimated by the receiver. In this case, the receiver may estimate the wireless channel state based on pilots transmitted from the transmitter.
The transmitter may transmit the pilots to the receiver using various methods.
As an example, a transmitter may decrease the number of data to be transmitted to a receiver, so as to insert a number of pilots in a frequency domain. For example, the transmitter may decrease the number of data up to an ‘x’ number of pilots in a frequency domain to insert the ‘x’ number of pilots. In this case, spectral efficiency may be deteriorated since the number of data to be transmitted to the receiver is decreased to insert the number of pilots.
As another example, a transmitter may eliminate data in a frequency domain and insert pilots in positions corresponding to the eliminated data. In this case, distortion may exist in a time domain signal since there are eliminated data in the frequency domain.
Accordingly, there is needed a technique that may reduce the distortion of a signal without deteriorating efficiency of a frequency.